3. 5-cm potato cubes are individually quick frozen (IQF) in a blast freezer operating at -40 C and with a surface heat transfer coefficient of 30 W/m/K. If the freezing point of the potato is measured as -1 C and the density is 1180 kg/m, calculate the freezing time for each cube. If the cubes are then packed into a cardboard carton measuring 20 cm x 10 cm x 10 cm, calculate the relative freezing time. Given: Latent heat of crystallization of water = 335 kJ/kg Moisture content of potato = 81.8% Thickness of card = 1.5 mm Thermal conductivity of card = 0.07 W/m/K Thermal conductivity of potato = 2.5 W/m/K